fsl_i2c: increase I2C timeout values and make them configurable

The value of I2C_TIMEOUT in fsl_i2c.c has several problems.  First, it is
defined as CONFIG_HZ/4, but it is used as a count of microseconds, so it makes
no sense to derive it from a clock rate.  Second, the current value (250) is
too low for some boards, so it needs to be increased.  Third, the timeout
necessary for multiple-master arbitration is larger than the timeout for basic
read/write operations, so we shouldn't have a single constant for both timeouts.
Finally, it would be nice if we could override these values on a per-board
basis.

Signed-off-by: Timur Tabi <timur@freescale.com>
Acked-by: Wolfgang Denk <wd@denx.de>
Tested-by: Peter Tyser <ptyser@xes-inc.com>
Acked-by: Peter Tyser <ptyser@xes-inc.com>

drivers/i2c/fsl_i2c.c

@@ -1,5 +1,5 @@
 /*
- * Copyright 2006 Freescale Semiconductor, Inc.
+ * Copyright 2006,2009 Freescale Semiconductor, Inc.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
@@ -26,7 +26,21 @@
 #include <asm/io.h>
 #include <asm/fsl_i2c.h>	/* HW definitions */
 
-#define I2C_TIMEOUT	(CONFIG_SYS_HZ / 4)
+/* The maximum number of microseconds we will wait until another master has
+ * released the bus.  If not defined in the board header file, then use a
+ * generic value.
+ */
+#ifndef CONFIG_I2C_MBB_TIMEOUT
+#define CONFIG_I2C_MBB_TIMEOUT	100000
+#endif
+
+/* The maximum number of microseconds we will wait for a read or write
+ * operation to complete.  If not defined in the board header file, then use a
+ * generic value.
+ */
+#ifndef CONFIG_I2C_TIMEOUT
+#define CONFIG_I2C_TIMEOUT	10000
+#endif
 
 #define I2C_READ_BIT  1
 #define I2C_WRITE_BIT 0
@@ -213,9 +227,10 @@ static __inline__ int
 i2c_wait4bus(void)
 {
 	unsigned long long timeval = get_ticks();
+	const unsigned long long timeout = usec2ticks(CONFIG_I2C_MBB_TIMEOUT);
 
 	while (readb(&i2c_dev[i2c_bus_num]->sr) & I2C_SR_MBB) {
-		if ((get_ticks() - timeval) > usec2ticks(I2C_TIMEOUT))
+		if ((get_ticks() - timeval) > timeout)
 			return -1;
 	}
 
@@ -227,6 +242,7 @@ i2c_wait(int write)
 {
 	u32 csr;
 	unsigned long long timeval = get_ticks();
+	const unsigned long long timeout = usec2ticks(CONFIG_I2C_TIMEOUT);
 
 	do {
 		csr = readb(&i2c_dev[i2c_bus_num]->sr);
@@ -251,7 +267,7 @@ i2c_wait(int write)
 		}
 
 		return 0;
-	} while ((get_ticks() - timeval) < usec2ticks(I2C_TIMEOUT));
+	} while ((get_ticks() - timeval) < timeout);
 
 	debug("i2c_wait: timed out\n");
 	return -1;